Embodiments of the invention are directed, in general, to communication systems and, more specifically, a hybrid-ARQ (HARQ) with a scrambler.
In a wireless communication system, it is impossible for a device to decode all of the packets correctly. The packet may fail because of, inter alia:                A low signal-to-noise ratio (SNR)        Interference        Clipping at the transmitter due to peak-to-average ratio (PAR)        
One common method that is used to assure that all packets are delivered correctly is called automatic-repeat request (ARQ). In this method, the receiving device sends either an acknowledgement (ACK) or a negative-acknowledgement (NACK) to the transmitting device regarding the decode-status of the packets. If the transmitting device receives a NACK or times out waiting for the ACK/NACK, it will then retransmit that packet. This process continues until the receiving device successfully decodes the packet or opportunity to transmit the packet expires, which is also called a time-out.
A further improvement upon the ARQ scheme is called hybrid-ARQ (HARQ). In this method, the receiving device will combine the soft information from (for example Chase combining or any other well-known method for combining soft information such as LLRs) a retransmission with the original transmission to increase the probability of correctly decoding the packet. This performance improvement comes at the cost of a slight increase in complexity at the receiver.